Fungal diseases

What is a disease

Disease is an impairment of the normal state of the plant or of any of its components that interupts or modifies the performance of the vital function, being a response to environmental factors, to specific infective agents, to inherent defects of the plant, or to combinations of these factors.

What is a fungus

Fungus is a multi-celled parasitic plant that has no leaves and true stems and roots. It lacks the green color. Its reproduction is by spores which are tiny seedlike structures that grow up to 1 mm in size. Mushroom, mold, and mildew are examples the mostly seen fungi.

Meanings of sign and symptom

Sign is the infectious disease itself and its products, examples are; fungal spores, fungal growths, sooty molds, cankers, galls, slimy ooze, and fishy odor

Symptom is the plant's response to the disease causing organism, examples are; changes in plant color, death of infected tissues, and wilting.

Signs and symptoms of fungal diseases

Blights are the appearance of streaks on leaves, stems, and fruits that include early and late blights that mostly attack tomatoes, potatoes, eggplant, pepper, and their relatives. Blight is a disease condition wherein an affected plant part is dried or dead but not rotten and has yellow or dead tissues. It also cause any sudden, severe, and extensive spotting, discoloration, or destruction of leaves, flowers, stems, or the entire plants and usually attacking young, growing tissues. The disease names are often coupled with the names of the affected part of the host; e.g., leaf blight, blossom blight, shoot blight, stem blight.

Cankers are dead areas on a stem or fruit surrounded by living cortical tissues.

Club roots are the large swelling of roots, stunted growth or death of cabbage and its relatives.

Damping-off kills seedlings before soil emergence as well as the newly emerged ones. The stem rots occurred right on the soil line.

Galls are outgrowths or swellings of un-organized plant cells.

Mildews are the white spots or patches on leaves, shoots, and other plan parts. Downy mildew kills the infected plant fast, while powdery mildew causes stunted growth, stressed plant, and reduced yield but not killing the plant.

Root rots are the killing of the rootlets that cause stunting and wilting.

Rusts are the orange, brownish, or white spots on the leaves and stems.

Scabs appear corky and cracked on infected fruit.

Spots of yellow, orange, gray, brown, tan, purplish, red, or black on the plant parts are caused by several species of disease causing fungi like; anthracnose, Alternaria, Fusarium, Cercospora, etc.

Smuts are the silver swellings or galls on leaves, flowers, tassels, and stems. They enlarge, darkened, and break open to expose the masses of black fungal spores.

Wilts are fungal damages wherein the plants' water conducting vessels are plugged causing the leaves to wilt and die.

Prevention and control

1. Always make a plan to grow a healthy crop
2. Properly select plant cultivars that are fungal resistant and are common in your locality
3. Have proper plant spacing by following the recommended planting distances. This enables light penetration and air flow
4. Have a healthy and well-balanced soil
5. Prune the overcrowded foliage
6. Pick and cut the infected plant parts
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7. Uproot the heavily infected plants
8. Always practice proper field sanitation
9. Control the weeds
10. Practice crop rotation by alternating crops of non-related family groups during every cropping season
11. Spray your crops with homemade plant extracts and/or other homemade solutions like any of the following;
    Aloe
    Basil
    Coriander
    Garlic
    Ginger
    Horsetail
    Lemongrass
    Malabar nut
    Mint
    Neem
    Onion
    Papaya
    Pongam
    Turmeric
    Animal urine
    Baking soda
    Compost tea
    Horticultural oil
    Milk spray
    Soap spray
    

References

• Brooklyn Botanic Garden. (2000): Natural disease control: A common-sense approach to plant first aid. Handbook # 164. Brooklyn Botanic Garden, Inc. 1000 Washington Avenue, Brooklyn, NY.
• Ellis, B.; Bradley, F. (1996): The organic gardener's handbook of natural insect and disease control. Rodale Press. Emmaus, Pennsylvania.
• Gilberg, L. editor. (1993): Garden pests and diseases. Sunset books. Sunset Publishing Corporation, California.
• Olkowski, W.; Daar, S.; Olkowski, H. (1995): The gardener?s guide to common-sense pest control. The Taunton Press. USA.
• Ploetz, R.; et. al. Editors. (1998): Compendium of tropical fruit diseases. APS Press, The American Phytopathological Society. Saint Paul, Minnesota, USA.
• Thurston, D. (1998): Tropical plant diseases. Second Edition. APS Press. The American Phytopathological Society. St. Paul, Minnesota, USA.